Starting mechanism for internal combustion engines



STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed on. 10, 1966 Sept. 3, 1968 5E|LLY ET AL 2 Sheets-Sheet 1 Sept. 3, 1968 A. H. SEILLY ET AL 3,399,576

STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Filed om 10, 1966 2 Sheets-Sheet z a 2 I 77w wi United States Patent 3,399,576 STARTING MECHANISM FOR INTERNAL COMBUSTION ENGINES Alec Harry Seilly, North Wembley, England, assignor to .C.A.V. Limited, London, England Filed Oct. 10, 1966, Ser. No. 585,618 Claims priority, application Great Britain, Oct. 22, 1965,

44,764/65 10 Claims. (Cl. 74-7) ABSTRACT OF THE DISCLOSURE A starting mechanism for an internal combustion engine and the mechanism comprising an electric motor incluoing a rotor, a shaft extending through the rotor and pro jecting beyond one end thereof the projecting portion of the shaft having an axially movable pinion operatively connected thereto. The mechanism also including a device for moving the pinion axially to an operative position in which it engages with a toothed wheel of the engine and there also being provided a one way clutch which ispositioned within the rotor and which acts to transmit driving torque between the rotor and the shaft.

This invention relates to starting mechanism for internal combustion engines and has for its object to provide such a mechanism in a simple and convenient form.

A starting mechanism in accordance with the invention comprises in combination, a motor, a shaft arranged to be driven by the motor, an axially movable pinion operatively connected to the shaft, a device for moving the pinion axially to an operative position in which it is engaged with the toothed wheel of an engine, and a one way clutch disposed intermediate the shaft and the motor, the arrangement being such that in'the event of the pinion being maintained in its operative position when the engine has started the clutch will act to prevent the motor being driven by the engine.

In the accompanying drawings:

FIGURE 1 is a sectional side elevation of one example of a starting mechanism in accordance with the invention,

FIGURE 2 is a section on the line 22 of FIGURE 1,

FIGURE 3 is a sectional side elevation of part of a modification of the mechanism shown in FIGURE 1,

FIGURE 4 is a sectional side elevation of part of another modification of the mechanism shown in FIGURE 1, and 7 FIGURE 5 is a sectional side elevation of a modification of the mechanism of FIGURE 3.

Referring to FIGURE 1 of the drawings there is pro vided a rotor armature 1 having an extended axial shaft 2. Slidably mounted on the shaft and rotatable therewith is a non-magnetic sleeve 3 having secured thereto a pinion 4. The pinion and shaft are inter-connected by a quick pitch screw thread 8 whereby when the shaft is rotated in one direction relative to the pinion the latter will be moved axially away from the armature 1 into mesh with teeth formed on the periphery of a flywheel 5 of the associated engine against the action of a compression spring 6 located between the pinion and an abutment 7 on the end of the shaft. The sleeve 3 is surrounded by an axially slidable hollow cylindrical iron Patented Sept. 3, 1968 an annular step 10a on the sleeve so as to permit limited relative axial movement of the core and sleeve.

Also mounted on the sleeve 3 is an axially slidable collar 12 which is loaded by a compression spring 13 and serves to move a plurality of catch balls 14 into engagement with an annular shoulder 15 in the shaft 2 for securing the sleeve to the shaft when the pinion 4 is moved into engagement with the teeth on the flywheel 5 of the engine so preventing inadvertent return of the sleeve to its rest position before the engine has been fully started.

Adjacent the end of the solenoid nearest the armature is an annular electrically insulating disc 16 which carries a pair of fixed contacts 17, 18 forming part of two electric switches respectively. The moving contacts 19, 20 of the switches are carried by a substantially rectangular titltable member 21 located about a hollow member 22 mounted on the core 9 and loaded against a flange on the shoulder by a coiled compression spring 23 of helically coiled conical form. A further compression spring 9b is interposed between the housing and the core 9 to urge the core towards the armature. At one angular'position on the member 21 there is provided a tongue piece 24 and extending from the disc 16 towards the armature at substantially the same angular position as the tongue piece 24 is a support 25 having pivotally mounted thereon a catch 26 in the form of a bell crank lever. On one arm of the catch is a projection 27 to engage over the tongue piece in the manner of a hook.

The catch is loaded into engagement with the tongue piece by means of a spring 29 surrounding the pivot 25 one end of the spring bearing on the other arm of the catch and the other end of the spring bearing on the end of the core. Mounted on the end of the sleeve nearest the armature is an annular catch release plate 30 provided to co-operate with the other arm of the catch when the sleeve moves away from the armature as during the starting sequence.

Also provided is a one way clutch 40 which is accommodated within the armature and which serves as a driving connection between the rotor and the shaft 2. The clutch illustrated in section in FIGURES 2 is a clutch of the roller type and includes an inner member 41 of plain hollow cylindrical form which is keyed or otherwise non-rotatably engaged with the shaft 2. The outer member of the clutch is secured to the rotor and formed in the internal periphery thereof are a plurality of tapering recesses in which are located rollers 42 respectively the latter being located within a cage. The operation of this type of clutch is well known.

In use when the solenoid 10 is energised, by closure of a switch (not shown), the core 9 and all the parts mounted thereon move axially away from the armature. When the shoulder 9a on the core abuts against the step 3a on the sleeve the sleeve is urged :by the core axially away from the armature against the action of the spring 6 and effects the initial engagement of the pinion 2 with the teeth of the flywheel 5. At the same time the tongue 24 on the member 21 abuts against the projection 27 on the catch and the member is tilted against the action of the spring 23, allowing the contacts 17 and 19 to close and permitting the rotor to be energised through a resistance (not shown). As the armature 1 is rotated the shaft is driven through the clutch 40 and the pinion is moved into full engagement with the teeth on the flywheel, due to the action of the quick pitch screw-thread 8 and as the armature is rotating slowly, because of the resistance in the circuit, the engagement will be smooth.

As soon as the pinion is in full engagement 'With the flywheel the catch balls 14 will move into position against the shoulders 15 to retain the sleeve relative to the shaft. Moreover, the collar will move relatively to the shaft and the balls will be retained positively in this position by the plain portion of the collar. Immediately prior to full engagement the catch release plate moves the catch 26 angularly to release the tongue 24 and allow the contacts 18, 20 to close. Closure of the contacts 18, 20 short circuits the resistance and full power is developed by the motor to rotate the flywheel.

Since one end of the spring 29 abuts against the core the spring force on the catch is reduced as the core moves axially. Consequently when the catch release plate 30, which is rotating, contacts the relatively non-rotating catch, wear on the parts will be minimised. Moreover, minimum force is required to release the catch.

After the engine has been set in rotation the switch in the solenoid circuit is re-opened the core first moves the collar to unlock the catch balls 14 whereafter the various parts are restored to their initial position by the screw connection between the shaft and the sleeve.

In the event that the switch in the solenoid circuit is maintained closed after the engine has started the flywheel will drive the pinion and the rest of the mechanism.

However, by providing the one way clutch the armature will not be driven at an excessive speed with the result that the risk of damage thereto is minimised.

In the arrangement shown in FIGURE 3 the clutch 40 is of the multiplate type but the remaining parts of the mechanism are identical to those described above. Referring to FIGURE 3 the clutch 40 comprises an inner member of hollow cylindrical form. On the internal periphery of this member is formed a quick pitch thread which is engaged with a complementarily shaped thread formed on the periphery of the shaft 2. On the external periphery of the, member 50 is formed a plurality of axially extending splines and also an outwardly extending flange 51. Engaged with the splines are a plurality of driven annular clutch plates 52. Interposed between driven clutch plates are annular driving clutch plates 53 which are in engagement with splines formed on the internal periphery of an outer clutch member 54, the latter being nonrotatably connected to the armature. The end plate of the pack of clutch plates remote from the flange 51 is a driving plate and bearing upon this plate is a coiled compression spring 54a surrounding the shaft and having its end remote from the pack located within an annular groove formed in the outer clutch member.

The member 50 can move in opposite directions relative to the shaft the extent of movement of the member being limited by stops 55 and 56 formed on the outer clutch member and a flanged cylindrical member 57 which freely surrounds the shaft but which is nonrotatably engaged with the outer clutch member 54. The member 57 is urged against a step on the shaft and interposed between the flange of the member and the flange 51 is a coiled compression spring 58.

In use, the spring 58 maintains the clutch plates in light frictional engagement and when the armature starts to rotate rotary motion is imparted to the shaft by way of the clutch plates and the quick pitch thread, when the pinion is fully engaged the action of the quick pitch thread between the shaft and the member 50 is to load the clutch plates and to compress the spring 54a. Thus the clutch transmits the torque from the armature which is required to start the engine. The extent of compression of the spring 54a is limited by the abutment of the member 50 with the stop 55 and if the member is in contact with the stop and the torque required to rotate the engine increases then the clutch will slip to prevent damage to the mechanism.

When the engine drives the motor the member 50 by the action of the quick pitch thread will 'be moved into contact with the stop 56 and the spring 58 will be compressed. In this position the driving and driven clutch plates are separated from each other and the armature speed which can be attained will be its no-load running speed or possibly due to drag of the clutch plates slightly higher.

The arrangement shown in FIGURE 5 is substantially the same to that shown in FIGURE 3 with the exception that the spring 54a is omitted and also the stop 55. The effect of this is that the member 50 moves axially to compress the clutch plates to a degree such that whatever torque is required to be transmitted by the clutch is transmitted. In other words the clutch does not limit the torque which can be transmitted between the motor and the shaft.

In FIGURE 4 there is shown a further arrangement of the clutch 40 and in this case a ratchet clutch is provided. As shown in FIGURE 4 the clutch comprises a driven member 60 which is in quick pitch screw thread engagement with the shaft 2 and a driving member 61 which is in axially extending spline engagement with the internal periphery of a hollow cylindrical part 61a driven by the armature 1. The presented faces of the members 60 and 61 are provided with interengaging ratchet teeth 62 and a coiled compression spring 63 is provided to load the teeth into driving engagement. Moreover, a resilient cushion 64 is provided intermediate the driving member 61 and a radially extending face formed on the cylindrical part 61a. When the armature is driving the shaft the quick pitch thread urges the ratchet teeth into tight engagement but when the engine drives the shaft the action of the quick pitch thread is to separate the members 60 and 61 against the action of the spring 63 and ratcheting of the teeth 62 occurs.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A starting mechanism for internal combustion engines and comprising in combination, an electric motor including a rotor, a shaft extending through the rotor and projecting beyond one end thereof, an axially movable pinion operatively connected to the projecting end of the shaft, a device for moving the pinion axially to an operative position in which it is engaged with a toothed wheel of an engine, and a one way clutch serving to transmit driving torque from the rotor to the shaft said clutch being positioned within the rotor so that the projecting portion of the shaft together with a portion of the shaft lying within the rotor is available to absorb shock loads resulting from the engagement of the pinion and toothed wheel, the clutch acting to prevent the rotor being driven by the engine.

2. A starting mechanism as claimed in claim 1 in which the clutch is of the roller type.

3. A starting mechanism as claimed in claim 1 in which the clutch is of the ratchet type having a driving and a driven member carrying. interengaging ratchet teeth.

4. A starting mechanism as claimed in claim 3 including means for urging the teeth into engagement when the motor is driving the shaft and for moving the teeth out of engagement when the shaft tends to drive the motor.

5. A starting mechanism as claimed in claim 4 in which said means comprises a quick pitch thread formed on the shaft and a complementary thread formed on one of said members.

6. A starting mechanism in claim 5 in which resilient means is provided to urge the teeth into engagement.

7. A starting mechanism as claimed in claim 1 in which the clutch is a multiplate friction clutch means being provided to urge the plates of the clutch into frictional engagement with each other so that the motor can drive the shaft and for allowing the plates to separate when the shaft tends to drive the motor.

8. A starting mechanism as claimed in claim 7 in which said means comprises a quick pitch screw thread formed on the shaft and a complementary thread formed on a part surrounding the shaft to support one set of plates of the clutch.

5 6 '9. A starting mechanism as claimed in claim .8 in which References Cited resilient means is provided to load the clutch plates into UNITED STATES PATENTS light frictional engagement when the mechanism is at rest.

10. A starting mechanism as claimed in claim 9 in 1,939,405 12/1933 Mardone 7 XR which the plates are loaded against the action of resilient 5 2,333,765 11/ 1943 Celio 747 XR means, the extent of loading permitted by said resilient 2,727,158 12/1955 Seilly 74--7 XR means being limited so that the clutch can act as an overload clutch. WENDELL E. BURNS, Primary Examiner. 

